JP3769497B2 - Vacuum microwave thawing method and vacuum microwave thawing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum microwave thawing method for heating and thawing an object to be thawed such as frozen food by irradiating microwaves while repeatedly performing a decompression step and a decompression step, and a vacuum microwave for performing the thawing method. Regarding the decompressor.
[0002]
[Prior art]
A conventional vacuum microwave thawing machine is an apparatus that heats a material to be thawed by irradiating microwaves in a pressure reduction process while repeatedly performing a pressure reduction process and a pressure reduction process. The vacuum microwave thawing machine of this type includes a chamber for containing the material to be thawed, a vacuum pump for decompressing the inside of the chamber, a decompression means for decompressing the inside of the chamber decompressed by the vacuum pump, and the decompression In the process, a microwave generator for irradiating microwaves into the chamber is provided. Generally, the size of the chamber and the capacity of the vacuum pump are fixed elements, not variable elements.
[0003]
[Problems to be solved by the invention]
By the way, in the conventional thawing method using a vacuum microwave thawing machine, the amount of water vaporized in the chamber varies depending on the weight of the material to be thawed. . Further, in order to defrost to a desired temperature, the required heat energy (that is, microwave output and irradiation time) varies depending on the weight of the material to be thawed. Therefore, when the chamber size and the capacity of the vacuum pump are constant, when performing the thawing operation, the weight of the material to be thawed must be individually input as an initial set value each time. It was necessary to adjust the wave output and microwave irradiation time, and the operation was complicated.
[0004]
Therefore, the present invention can automatically control the microwave output and microwave irradiation time according to the weight of the object to be thawed without individually inputting the weight of the object to be thawed as an initial set value each time. An object of the present invention is to provide a vacuum microwave thawing method and a vacuum microwave thawing machine.
[0005]
[Means for Solving the Problems]
The present invention has been proposed in view of the above, and according to the first aspect, the object to be thawed is irradiated with microwaves while repeatedly performing the decompression step and the decompression step under the control of the control device. In a vacuum microwave thawing method that performs heating and thawing,
In advance, the amount of change in pressure reduction of the standard sample is set in the control device as a standard value based on the correlation with the weight,
In the preliminary drying step in which the pressure is first reduced without irradiating with microwaves, the amount of change in pressure in the chamber containing the material to be thawed is measured, and the amount of change in pressure measured is compared with the standard value, and then the correlation is obtained from the above correlation. A vacuum microwave thawing method characterized by estimating a weight of a thawing product and controlling a microwave output and / or a microwave irradiation time according to the weight.
[0006]
According to a second aspect of the present invention, there is provided the vacuum microwave thawing method according to the first aspect, wherein the reduced pressure change amount is performed by comparing a reduced pressure arrival time to reach a reduced pressure equilibrium region.
[0007]
According to a third aspect of the present invention, there is provided the vacuum microwave thawing method according to the first aspect, wherein the amount of change in pressure reduction is performed by comparing the ultimate pressure reduction degree in a pressure reduction equilibrium region.
[0008]
According to a fourth aspect of the present invention, there is provided a chamber for containing an object to be thawed, a vacuum pump for reducing the pressure in the chamber, a pressure regulating valve for returning the pressure in the chamber, and a microwave generator for irradiating the chamber with microwaves. And a control device for controlling the vacuum pump, the pressure regulating valve, and the microwave generator. Under the control of the control device, the object to be thawed is irradiated with microwaves while repeating the decompression step and the decompression step. In a vacuum microwave thawing machine that heats and defrosts ,
The amount of change in vacuum of the standard sample can be set in advance as a standard value based on the correlation with its weight, and the pressure in the chamber containing the material to be thawed is reduced in the preliminary drying step in which pressure is first reduced without irradiation with microwaves. Comparing the amount of change in vacuum actually measured with the above standard value, estimating the weight of the object to be thawed from the above correlation, and controlling the microwave output and / or microwave irradiation time according to this weight It is a vacuum microwave defroster characterized by having a control device .
[0009]
According to a fifth aspect of the present invention, in the vacuum microwave thawing according to the fourth aspect, the controller is configured to compare the amount of change in pressure input to the control device by comparing the arrival time of the reduced pressure reaching the reduced pressure equilibrium region. Machine.
[0010]
The pump of Claim 6, wherein the controller, decompression amount of change, vacuum microwave thawing machine according to claim 4, characterized in that the comparison of the arrival vacuum degree of vacuum equilibrium zone for inputting thereto It is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the appearance of the vacuum microwave defroster of the present embodiment. FIG. 2 is a schematic view showing main components in the vacuum microwave defroster of the present embodiment.
[0012]
As shown in FIG. 1, the vacuum microwave thawing machine 1 of the present embodiment is provided with a food container 3 for storing an object to be thawed such as frozen food at the upper part of a housing 2, and will be described below at the lower part. A machine storage unit 4 for storing a drive motor, a vacuum pump, and the like is disposed, and a control unit 5 for storing a control device is provided at the top, and a front panel of the control unit 5 has a thawing object. A display unit 6 that displays weight, thawing time, and the like, and an operation unit 7 that inputs power on / off, the type of an object to be thawed, and the like are provided. In addition, a caster 8 for facilitating the movement of the thawer 1 is provided on the lower surface of the casing 2 of the vacuum microwave thawer 1.
[0013]
As shown in FIGS. 1 and 2, the main body of the food container 3 in the vacuum microwave thawing machine 1 of the present embodiment is constituted by a hollow box-shaped chamber 10 having an opening on the front surface, and the chamber 10 is an electromagnetic wave. It is formed as a pressure-tight and airtight container having an inner wall structure capable of blocking. A door 11 capable of closing the inside of the chamber 10 in a sealed state is attached to the front opening of the chamber 10 through a hinge portion at the right front end of the chamber 10 so as to be openable and closable. On the left side of the front surface, a handle 12 is attached for holding the opening / closing operation. On the front surface of the chamber 10 or on the back surface of the door 11, an electromagnetic wave seal made of a metal mesh string and an airtightness for preventing leakage of electromagnetic waves to the outside A hermetic seal is installed to maintain
[0014]
At the bottom of the chamber 10, a rotating shaft 13 is rotatably supported in a state where it is supported by a bearing 14, and an object to be thawed facing the chamber 10 is provided at the upper end of the rotating shaft 13. A turntable 15 that rotates together with the rotary shaft 13 is detachably attached, and a table drive motor 16 is connected to a base end portion of the rotary shaft 13 via a speed reduction mechanism.
[0015]
A central portion of the back surface of the chamber 10 is placed on the turntable 15 by irradiating the chamber 10 with microwaves via a straight waveguide 20 and a reducer waveguide 21 communicating with the chamber 10. A microwave generator 22 for heating the object to be thawed is connected. In this embodiment, a magnetron is employed as the microwave generator 22, and a pressure partition made of a glass plate that easily transmits microwaves to the flange connection portion 23 between the straight waveguide 20 and the reducer waveguide 21. Is installed.
[0016]
A discharge detection sensor 30 is provided on the back surface of the chamber 10 to detect when a discharge occurs in the chamber 10 due to microwave irradiation. A UV sensor that is determined by detecting (UV) is employed. Further, a vacuum pressure sensor 31 for detecting the pressure in the chamber 10 is provided on the upper portion of the chamber 10. The vacuum pressure sensor 31 may be provided with a time measurement function, or the control device described later may be provided with a time measurement function so that the pressure change in the chamber 10 can be measured with time. Good.
[0017]
An upper part of the chamber 10 is provided with an air release valve 40 for releasing the pressure in the chamber 10 to the atmosphere, and a pressure regulating valve 41 for adjusting the pressure in the chamber 10. A decompression system 43 for reducing pressure is connected, and a vacuum pump 46 driven by a pump drive motor 45 is connected to the decompression system 43 via a check valve 44. It is stored in the machine storage unit 4.
[0018]
The air release valve 40 and the pressure regulating valve 41 are constituted by, for example, electromagnetic valves in order to enable opening / closing control by a control device housed in the control unit 5. The pressure regulating valve 41 may be provided in the middle of the pressure reducing system 43, for example, between the chamber 10 and the check valve 44, so that oxygen does not easily enter the chamber 10 in the pressure-reducing step.
[0019]
FIG. 3 is a block diagram showing a control system in the vacuum microwave defroster of the present embodiment. As shown in FIG. 3, the control device 50 housed in the control unit 5 is constituted by, for example, a microcomputer that executes a control program recorded in the ROM 51. The control device 50 rotates the turntable 15. A power control system 52 for the table drive motor 16 to be driven, a power control system 53 for the pump drive motor 45 for driving the vacuum pump 46, an open / close control system 54 for the atmospheric release valve 40, and an open / close control for the pressure regulating valve 41. A system 55, a power supply control system 56 of the microwave generator 22, a detection value input system 57 of the discharge detection sensor 30, and a detection value input system of the vacuum pressure sensor 31 (also a depressurization time input system of the time measurement function). 58), an input system 59 for setting values of the operation unit 7, and a display output system 60 of the display unit 6 are connected. The devices such as the pump drive motor 45 and the microwave generator 22 are driven according to the control program recorded in the ROM 51 based on the set values of the unit 7 and the detection values of the discharge detection sensor 30 and the vacuum pressure sensor 31. Control.
[0020]
Further, in the ROM 51 of the control device 50, the amount of change in the reduced pressure of the standard sample in the preliminary drying step up to the later-described reduced pressure equilibrium region is set in advance as a standard value based on the correlation with the weight, and the time measurement function is provided. The provided vacuum pressure sensor 31 measures the amount of change in pressure reduction in the chamber 10 containing the material to be thawed in the preliminary drying process, and inputs it to the control device 50 via the detection value input system 58. The reduced pressure change amount is compared with the standard value, the weight of the object to be thawed is estimated from the correlation between the reduced pressure change amount and the weight, and the microwave generator 22 is connected via the power supply control system 56 according to the weight. The control signal is output to the output of the microwave, and / or the irradiation time of the microwave is controlled. Vacuum reaches the reduced pressure equilibrium zone in the drying step arrival time or arrival vacuum degree or the like is used.
[0021]
Next, the vacuum microwave thawing method of the present embodiment performed using the vacuum microwave thawing machine 1 as described above will be described. FIG. 4 is an explanatory diagram showing a thawing cycle in the vacuum microwave thawing machine 1 of the present embodiment, and FIG. 5 is an explanatory diagram showing a weight estimation method of an object to be thawed in the vacuum microwave thawing method of the present embodiment. It is.
As shown in FIG. 4, the vacuum microwave thawing machine 1 of the present embodiment irradiates microwaves M and M while repeatedly performing the decompression steps G, G ′, G ″... And the decompression steps F, F ′. This is a device for heating and thawing the object to be thawed The vacuum pump 46 continues to operate with a constant suction capacity not only during the decompression process but also during the decompression process.
[0022]
As a preparation stage for thawing, first, the front door 11 is opened and an object to be thawed such as frozen food is placed on the turntable 15, and the door 11 is closed again to be in a sealed state. Contains the thaw. Note that the atmosphere release valve 40 and the pressure regulating valve 41 are closed.
[0023]
Next, the pump drive motor 45 is driven to operate the vacuum pump 46, and pressure reduction in the chamber 10 is started via the pressure reduction system 43. Then, the pressure reduction degree gradually decreases from 101.3 kPa (760 Torr) of the atmospheric pressure through the point A, and the pressure reduction step G is performed to the pressure reduction equilibrium region B. In this pressure reduction step G, the material to be thawed is pre-dried. . That is, the preliminary drying step is a step in which the pressure is first reduced without irradiation with microwaves.
[0024]
Here, the decompression equilibrium region is a region in which the degree of decompression with respect to a certain time is extremely reduced. For example, the degree of decompression (ΔP) in 30 seconds (Δt) is ΔP / Δt <13.3 Pa (0.1 Torr). Although it is sometimes grasped that the decompression equilibrium region has been reached, the equilibrium pressure in the decompression equilibrium region rises and falls due to the saturated vapor pressure in the chamber 10. Note that whether or not the decompression equilibrium region has been reached is determined by the control device based on the pressure signal from the vacuum pressure sensor 31.
[0025]
In this preliminary drying step, the reduced pressure change amount in the chamber 10 containing the material to be thawed is also measured with the elapse of the reduced pressure time by the vacuum pressure sensor 31, and the actually measured reduced pressure change amount is detected value input system 58. To the control device 50. As described above, as the amount of change in pressure input to the control device 50, in this embodiment, the time to reach pressure reduction or the degree of pressure reduction to reach the pressure reduction equilibrium region in the preliminary drying step is used.
[0026]
Further, as shown in FIG. 5, for example, a to-be-thawed material having a weight of 3 kg is used as a standard sample S, and a depressurization speed or an ultimate depressurization degree in the preliminary drying step is determined. ) Is set in the ROM 51 as a standard value based on the correlation with the weight.
[0027]
When the preliminary drying process is actually performed, the amount of water vaporized in the chamber 10 varies depending on the weight of the material to be thawed, so that the amount of change in reduced pressure (such as the time to reach the reduced pressure equilibrium region or the degree of reduced pressure reached) varies. become. That is, as shown in FIG. 5, in the case of the thawing object L that is lighter than 3 kg (that is, lighter than the standard sample S), the amount of water is less than that of the standard sample S, so It will be faster by t1 than the sample S, and the ultimate reduced pressure will be lower by p1 than the standard sample S. On the other hand, in the case of the material to be thawed H that is heavier than 3 kg (that is, heavier than the standard sample S), the amount of water is larger than that of the standard sample S. Thus, the ultimate pressure reduction is higher than the standard sample S by p2. If the amount of water varies depending on the type of material to be thawed, a plurality of standard samples S can be set according to the type of material to be thawed, and the type of material to be thawed can be selected using the operation unit 7. And
[0028]
Therefore, the control device 50 compares the actually measured amount of change in pressure reduction with the standard value set in the ROM 51, estimates the weight of the object to be thawed from the correlation between the amount of change in pressure reduction and the weight, and passes the power supply control system 56. By outputting a control signal to the microwave generator 22 in accordance with the pressure reduction arrival time (t1 or t2) and the ultimate pressure reduction degree (p1 or p2), that is, according to the estimated weight, Wave output and / or microwave irradiation time is controlled. That is, when the pressure reduction arrival time is faster by t1 or the ultimate pressure reduction degree is lower by p1, the microwave output is lowered accordingly, and / or the microwave irradiation time is shortened and the temperature rises rapidly. Avoid that. On the other hand, when the pressure reduction arrival time is delayed by t2 or the ultimate pressure reduction degree is high by p2, the microwave output is increased accordingly, and / or the microwave irradiation time is lengthened to efficiently thaw. As a result, the microwave output and the microwave irradiation time can be automatically controlled according to the weight of the object to be thawed without individually inputting the weight of the object to be thawed as an initial setting value each time. It prevents quality degradation after thawing of the thawing product.
[0029]
Further, in this embodiment, since pre-drying is performed when starting the thawing cycle described later, even if moisture from frost thaw adheres to the surface of the object to be thawed, it is thawed after removing it by pre-drying. It is possible to avoid concentration of irradiation even if microwaves described later are irradiated.
[0030]
After performing the decompression step G to the decompression equilibrium region B, the pressure regulating valve 41 is opened at a predetermined opening degree to be described later, and the process proceeds to the decompression step F. The degree of decompression in the decompression step F causes vacuum discharge. At the point C after exceeding C [set to 1.33 kPa (10 Torr) with some margin in this embodiment], microwave irradiation M by the magnetron 22 is started, and a preset recovery pressure is obtained. When the pressure is restored to the upper limit value D, the control device closes the pressure regulating valve 41 based on the pressure signal from the vacuum pressure sensor, and then proceeds to the pressure reducing step G ′ again. Then, the object to be thawed is heated by continuing the microwave irradiation M by the magnetron 22 up to the point A ′ before reaching the lower limit P1 at which the degree of decompression does not cause vacuum discharge. Stop irradiation.
[0031]
In this embodiment, it is assumed that the degree of pressure reduction in the decompression step F exceeds the lower limit value P1 at which no vacuum discharge occurs due to the elapse of T1 time (a predetermined time set in advance, for example, 10 seconds) from the pressure reduction equilibrium region B. At the time of the point, the microwave irradiation M by the magnetron 22 is started. However, the present invention is not limited to this, and the fact that the degree of pressure reduction in the decompression step F has reached the lower limit value P1 that does not cause vacuum discharge is reduced. Detection may be performed by a pressure signal from the pressure sensor 31, and the microwave irradiation M may be started based on the detection.
[0032]
In this embodiment, when the time points C, C ′... At which the microwave irradiation is started are adjusted, for example, delayed, the microwave irradiation time can be shortened and the weight is lighter than the standard sample. Applicable. Conversely, by accelerating C, C ′... (But after passing through P1), the irradiation time can be maximized, and the present invention can be applied when the weight is heavier than the standard sample. It is also possible to adjust the irradiation stop point described later.
[0033]
In the present embodiment, the lower limit P1 of the degree of decompression that does not cause vacuum discharge is set to 1.33 kPa (10 Torr) as described above. That is, at the point C after the degree of decompression in the decompression step F exceeds 1.33 kPa (10 Torr), the microwave irradiation M by the magnetron 22 is started and the decompression is restored to the preset decompression upper limit D. Then, the process proceeds to the decompression step G ′ again, and the object to be thawed is heated by continuing the microwave irradiation M by the magnetron to the point A ′ before the degree of decompression reaches 1.33 kPa (10 Torr). . As described above, since the microwave irradiation M is performed from the middle of the decompression process F to the decompression process G ′, one thawing cycle including the decompression process and the decompression process is performed as compared with the conventional case where irradiation is performed only in the decompression process. A sufficient irradiation time can be secured. Therefore, since the output of the microwave can be reduced with respect to the mass of the object to be thawed, the end face effect that is a phenomenon in which the microwaves concentrate on the corners of the object to be thawed does not occur.
[0034]
Moreover, since the microwave irradiation M is started from the point C where the degree of decompression in the decompression step F exceeds 1.33 kPa (10 Torr), the amount of water vaporized from the surface of the material to be thawed is small, and drying does not occur. At the same time, the decompression speed is not slow, and good thawing can be performed stably. Further, since the microwave irradiation M is performed in the range of the decompression degree of 1.33 kPa (10 Torr) or more, the discharge phenomenon hardly occurs in the chamber 10, and the microwave is sufficiently absorbed by the object to be thawed, and the thawing time is increased. Can be shortened, and stable thawing can be realized.
[0035]
The return pressure upper limit value D is a variable pressure value set by the output of the magnetron 22 that irradiates microwaves, the pressure reduction capability of the vacuum pump 46, and the volume of the chamber 10, and in this embodiment, the throttle of the pressure regulating valve 41 By adjusting the throttle of the valve 41 ′, it is set to 6.66 kPa (50 Torr). Therefore, when the pressure is restored to 6.66 kPa (50 Torr), the leak from the pressure regulating valve 41 and the suction capacity of the vacuum pump 46 balance, and the pressure rises while maintaining the pressure regulating valve 41 at 6.66 kPa (50 Torr). I do not.
[0036]
In the present embodiment, the pressure value of the decompression upper limit D is appropriately set in accordance with the output of the magnetron 22 that irradiates the microwave, the decompression capability of the vacuum pump 46, and the volume of the chamber 10, so that the vacuum discharge The microwave irradiation time without excess or deficiency can be taken before entering the generation area, and the pressure can be reduced efficiently.
[0037]
In this embodiment, as a means for detecting that the return pressure upper limit value D has been reached, it is detected by a signal from the vacuum pressure sensor 31 so that the control device closes the pressure regulating valve 43 and proceeds to the pressure reducing process. Although the present invention is configured, the present invention is not limited to this. For example, the present invention is based on time T2 from time C when microwave irradiation is started (similarly to T1, it is experimentally determined from the capacity of the vacuum pump and the volume of the chamber). You may control. Specifically, the time T2 from C may be set to 80 seconds, and when the 80 seconds have expired, the pressure regulating valve 43 may be closed and the process proceeds to the pressure reducing process.
[0038]
After the microwave irradiation is stopped, the object to be thawed is sublimated and cooled in the decompression process from the point A ′ to the decompression equilibrium region B ′. In this way, after the object to be thawed is heated by irradiating the microwave to the point A ′ in the decompression step G ′, the object to be thawed is sublimated and cooled in the decompression process from the point A ′ to the decompression equilibrium region B ′. When the object to be thawed is heated by irradiating with microwaves, the temperature of the surface part of the object to be thawed becomes higher than the temperature of the center part, and if heating is continued as it is, there will be inconveniences such as drip on the surface part. This is because the surface portion is cooled by sublimation to reduce the temperature difference between the inside and outside.
[0039]
That is, when sublimation starts, the latent heat of vaporization is deprived and the temperature of the surface portion decreases, and the heat of the surface portion moves (heat conduction) to raise the temperature of the central portion. As a result, the temperature of the material to be thawed is made uniform, and the temperature of the material to be thawed rises as a whole, and thawing is promoted. In addition, the thawing of the material to be thawed is promoted as a whole while the temperature of the material to be thawed is made uniform, so that thawing partially proceeds and drip is generated or microwaves concentrate on this drip. Can be prevented.
[0040]
In the present embodiment, the process proceeds to the decompression step F, and the microwave is generated at the point C after the decompression degree of the decompression step F exceeds the lower limit P1 of 1.33 kPa (10 Torr) that does not cause vacuum discharge. Irradiation M is started, and after returning to 6.66 kPa (50 Torr) which is a preset decompression upper limit D, the process proceeds to the decompression step G ′ again, and the degree of decompression is the lower limit P1 at which no vacuum discharge occurs. A thawing cycle in which microwave irradiation M is continuously heated to a point before A 'reaches 1.33 kPa (10 Torr), and after the microwave irradiation M is stopped, sublimation cooling is performed in the decompression process to the decompression equilibrium region B ′. Is repeated as one cycle.
[0041]
That is, in FIG. 4, after the decompression step G ′ is performed up to the decompression equilibrium region B ′, the process proceeds to the decompression step F ′, and the decompression degree of the decompression step F ′ is the lower limit value P1 at which no vacuum discharge occurs. At the point C ′ after exceeding 33 kPa (10 Torr), the microwave irradiation M ′ is started again, and after returning to 6.66 kPa (50 Torr) which is a preset decompression upper limit D ′, the pressure is reduced again. The process proceeds to step G ″, and the microwave irradiation M ′ is continuously heated until the pressure reaches 1.33 kPa (10 Torr) of A ″ which is the lower limit P1 at which the degree of decompression does not cause vacuum discharge. After the irradiation is stopped again, a defrosting cycle for sublimation cooling in the decompression process up to the decompression equilibrium region B ″ is performed as the second cycle. The decompression characteristics in each decompression process F, F ′. 41 'installation Because it depends on, constant in each thawing cycle, i.e., the curve of the condensate pressure curve is constant in each thawing cycle, which makes it possible to perform stable thawed.
[0042]
As shown in FIG. 4, when such a thawing cycle is repeated, the saturated vapor pressure in the chamber 10 increases as the temperature of the material to be thawed rises, so that the decompression equilibrium regions B, B ′, B ″. The depressurization degree of the above shows a phenomenon of increasing sequentially as the thawing cycle is repeated. Therefore, when the depressurization degree in the depressurization equilibrium regions B, B ′, B ″. That is, the desired thawing temperature can be set by setting the saturated vapor pressure region, and when the decompression equilibrium is reached in this setting region, the thawing operation is terminated assuming that the desired thawing temperature has been reached. The number of repetitions of the thawing cycle until reaching the set region also depends on the weight (mass) of the material to be thawed, the output of the magnetron 22, the decompression capacity of the vacuum pump 46, and the like. The pressure value of P2A at 480 Pa (3.6 Torr) and the pressure value of P2B is 453 Pa (3.4 Torr), and the degree of pressure reduction in the pressure reduction equilibrium regions B, B ′, B ″. When the temperature reaches, the thawing cycle is terminated assuming that the temperature of the material to be thawed is about -3 ° C.
[0043]
The set pressure values of P2A and P2B described above are values obtained by adding a width of 13.3 Pa (0.1 Torr) to the saturated vapor pressure when the finishing temperature is set to -3 ° C. It may be increased or decreased. Further, the finishing temperature is not limited to −3 ° C., but can be set to a desired temperature, and the P2A and P2B are set according to the saturated vapor pressure corresponding to the set temperature.
[0044]
When the end of the thawing cycle is determined in the control device 50, the atmosphere release valve 40 is opened, the power source of the pump drive motor 45 is shut off, the vacuum pump 46 is stopped, and the pressure of the vacuum pressure sensor 31 is 101. When 3 kPa (760 Torr) is shown, the door 11 can be opened, and the material to be thawed that has been thawed to about −3 ° C. can be taken out from the chamber 10.
[0045]
In addition, although the to-be-thawed material was demonstrated as frozen food in the said embodiment, the to-be-thawed material thawed by this invention is not limited to food, Blood, serum, semen, a medicine, etc. may be sufficient.
[0046]
【The invention's effect】
As is apparent from the above description, according to the present invention, in the preliminary drying step, the amount of change in reduced pressure such as the time to reach reduced pressure and the degree of reduced pressure reaching the reduced pressure equilibrium region in the chamber containing the material to be thawed is measured, Compare the measured amount of change in vacuum with a preset standard value, estimate the weight of the material to be thawed from the correlation between the weight and the amount of change in vacuum, and output microwave and / or microwave irradiation according to this weight Since the time is controlled, the microwave output and the microwave irradiation time are automatically controlled according to the weight of the object to be thawed without inputting the weight of the object to be thawed as an initial setting value each time. Efficient thawing can be performed without degrading the quality, and the operation is simple.
[Brief description of the drawings]
FIG. 1 is a front view showing an appearance of a vacuum microwave defroster according to an embodiment of the present invention.
FIG. 2 is a schematic view showing main components in the vacuum microwave defroster of the present embodiment.
FIG. 3 is a block diagram showing a control system in the vacuum microwave defroster of the present embodiment.
FIG. 4 is an explanatory diagram showing a thawing cycle in the vacuum microwave thawing machine of the present embodiment.
FIG. 5 is an explanatory diagram showing a weight estimation method of an object to be thawed in the vacuum microwave thawing method of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum microwave thawing machine 2 Housing | casing 3 Food storage part 4 Machine storage part 5 Control part 6 Display part 7 Operation part 8 Caster 10 Chamber 11 Door 12 Handle 13 Rotating shaft 14 Bearing 15 Turntable 16 Table drive motor 20 Direct guide Wave tube 21 Reducer waveguide 22 Microwave generator (magnetron)
23 Flange connection 30 Discharge detection sensor 31 Vacuum pressure sensor 40 Atmospheric release valve 41 Pressure regulating valve 43 Depressurization system 44 Check valve 45 Pump drive motor 46 Vacuum pump 50 Controller 51 ROM
52 Table Drive Motor Power Supply Control System 53 Pump Drive Motor Power Supply Control System 54 Atmospheric Open Valve Open / Close Control System 55 Pressure Regulator Open / Close Control System 56 Microwave Generator Power Supply Control System 57 Detection Value Input System 58 for Discharge Detection Sensor Detection value input system 59 for the vacuum pressure sensor Input system 60 for setting values for the operation unit Display output system for the display unit

Claims (6)

In the vacuum microwave thawing method in which the object to be thawed is heated and thawed by irradiating microwaves while repeatedly performing the decompression step and the decompression step under the control of the control device,
In advance, the amount of change in pressure reduction of the standard sample is set in the control device as a standard value based on the correlation with the weight,
In the preliminary drying step in which the pressure is first reduced without irradiating with microwaves, the amount of change in pressure in the chamber containing the material to be thawed is measured, and the amount of change in pressure measured is compared with the standard value, and then the correlation is obtained from the above correlation. A vacuum microwave thawing method characterized by estimating a weight of a thawing product and controlling a microwave output and / or a microwave irradiation time according to the weight.   2. The vacuum microwave thawing method according to claim 1, wherein the amount of change in pressure reduction is performed by comparing a time required to reach a pressure reduction equilibrium region.   The vacuum microwave thawing method according to claim 1, wherein the amount of change in pressure reduction is performed by comparing the degree of pressure reduction reached in a pressure reduction equilibrium region. A chamber for containing an object to be thawed, a vacuum pump for depressurizing the inside of the chamber, a pressure regulating valve for returning the pressure inside the chamber, a microwave generator for irradiating microwaves into the chamber, the vacuum pump, the pressure regulating valve and the micro A vacuum microwave that has a control device for controlling the wave generator and that heats the material to be thawed by irradiating the microwave while repeating the decompression step and the decompression step under the control of the control device. In the decompressor ,
The amount of change in vacuum of the standard sample can be set in advance as a standard value based on the correlation with its weight, and the pressure in the chamber containing the material to be thawed is reduced in the preliminary drying step in which pressure is first reduced without irradiation with microwaves. Comparing the amount of change in vacuum actually measured with the above standard value, estimating the weight of the object to be thawed from the above correlation, and controlling the microwave output and / or microwave irradiation time according to this weight A vacuum microwave thawing machine characterized by having a control device . 5. The vacuum microwave defroster according to claim 4, wherein the control device performs a reduced pressure change amount input thereto by comparing a reduced pressure arrival time to reach a reduced pressure equilibrium region. 5. The vacuum microwave defroster according to claim 4, wherein the control device performs the amount of change in pressure input to the controller by comparing an ultimate pressure reduction degree in a pressure reduction equilibrium region.

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